The UK's biggest political donor, Lord Sainsbury, has quit politics for charitable giving

Progress is holding its annual conference this weekend (Source: Getty)

Helen Cahill

Heavyweight political donor Lord David Sainsbury has ended his financial support for political causes, forcing Labour pressure group Progress to search for funding elsewhere.

Sainsbury, who donated £260,000 to the centrist think tank in 2016, will be focusing his efforts on charities from now on, the Guardian reported.

Writing on Progress' website, Richard Angell, the group's director, said Sainsbury's donations had "enabled new thinking and inspired new activists".

"It provides a platform for those wanting to encourage new avenues of policy thinking and challenge the mainstream Labour thinking when it needs updating and moving on," he wrote.

The think tank learned of Sainsbury's decision before the General Election and has since been looking for alternative sources of funding, including a "members-led model", Angell said today. He added that Progress had reached a third of its funding target over the past five weeks.

Sainsbury, former chair of the supermarket, was central to the funding efforts behind the campaign to remain in the European Union. He donated £2m to the Labour party and the Liberal Democrats in the weeks before the Brexit vote.